The present invention relates to battery charging in general and more particularly to a low cost highly efficient battery charging circuit particularly useful for mobile computers.
Mobile computers, for example, portable and lap top computers have the capability of operating from a rechargeable battery. This requires that the battery be periodically recharged. Such computers typically have built into them a battery charging circuit for this purpose. Either externally or internally to the computer box, line current is converted to a direct current of the desired value and reduced in voltage. Alternatively voltage from a dc source such a car battery is converted to an appropriate voltage. This voltage is then used through the battery charging circuit to recharge the battery. Typical circuits presently in use are linear circuits which have a relatively low efficiency. Furthermore, these prior art battery charging circuits are relatively costly and have a charging current which is a function of voltage. Thus, there is a need for a low cost, highly efficient battery charging unit.